Physiology Test #1

osmolarity

The measure of solute concentration in a solution, expressed as osmoles of solute per liter of solution. It is crucial for understanding fluid balance in the body.

molarity

mols/Liter

diffusion

the net movement of a certain type of molecule or atom that results from the combination of random molecular motion and a concentration gradient. Specifically net movement tends to go with the concentration gradient (high to low) due to the higher probability of a molecule moving from a region of higher concentration to one of lower concentration than vice versa

lysis

The process of breaking down or destroying cells, often resulting in the release of cellular contents.

Two things underlie the concept of individual organisms being able to make “responses”. One is that it involves the ability to adjust the rate of activity of one or more “processors” within the organism. The second is that it includes the notion of sensors able to monitor internal or external environmental changes, as that which initiates the rate adjustment? (T/F)

True, Organisms respond to changes by using sensors to detect environment shifts and adjusting their internal processing speeds.

Various forms of ions dissolved in water tend to move relatively freely through the lipid bilayer portion of a cell membrane? (T/F)

False, Charged ions cannot pass directly through the fatty membrane; they need specific protein channels.

In a solution where water is the solvent, the only thing that influences the osmolarity of the solution is the concentration of ions (that is, atoms or molecules with an unequal number of protons and electrons) within the solution. Other things dissolved in water (such as sugar molecules or amino acids) have no effect. (T/F)

False, Osmolarity counts all dissolved particles, including non-charged ones like sugars and amino acids.

Whenever a cell’s membrane is permeable to water, water molecules will tend to move at a faster rate from the region (either on the inside or the outside the cell) with the higher osmolarity to the region with lower osmolarity. (T/F)

False, Water flows toward higher osmolarity (where solute concentration is higher and water concentration is lower).

A cell’s “fundamental water problem” is that in addition to all the “background” solutes, all the molecules inside the cell associated with generating a “living” performance tend to generate an osmotic imbalance such that water molecules have a greater tendency to move into a cell—potentially to the point that the cell swells and even lyses.  (T/F)

True, Molecules inside a cell pull water inward, creating a constant risk of the cell bursting.

convection

A mass migration of molecules within a fluid (that is, a liquid or gas) that is powered by a pressure gradient.

Suppose you make two solutions. One you add 0.25 moles of sodium chloride (NaCl) to 1 liter of water. The other you add 0.25 moles of magnesium chloride (MgCl₂) to a liter of water. The osmolarity of the magnesium chloride solution will actually be higher than the osmolarity of the sodium chloride solution. (T/F)

True, MgCl2 breaks into 3 pieces per molecule, making its solution more concentrated than NaCl (which breaks into 2).

All the various forms of living cells found on earth solve their “fundamental water problem” by pumping out (via active transport) sodium ions. (T/F)

false, Plants, fungi, and bacteria use proton pumps and rigid cell walls instead of sodium pumps.

Given that both sodium ions (Na⁺) and calcium ions (Ca⁺⁺) are continually being pumped out of the cytoplasm of your cells, if negatively charged chloride ions (Cl^‑) were able to freely pass through a cell’s membrane, their net movement would continue to be into the cell until both the inside and outside of the cell has an equal concentration of positive and negative charges. (T/F)

False, Ions move until electrical and chemical forces balance out, not until charges inside and outside are identical.

Based on both charge and concentration gradients, the opening of an ion channel permeable to either sodium ions or calcium ions will result in the net movement of these ions into the cell. (T/F)

True, Both charge and concentration push Na+ and Ca+2 into the cell when channels open.

A common theme for cells within a multicellular organism that act as either “monitors” or “effectors” in an intercellular communication pathway, is that some change in the conditions outside of the cell leads to a change in the shape of certain proteins (that is, some but not all proteins) within the cell. (T/F)

True, Signal pathways work by altering the shape of specific target proteins inside the cell.

We have cells within our body in which certain forms of changes in their surrounding environment leads to the opening of calcium ion channels, and the subsequent influx of calcium ions alters the behavior of certain proteins in a way that triggers the release of other molecules by the cell via exocytosis. (T/F)

True, Calcium entering a cell triggers it to release chemical signals to the outside.

While water-soluble signal molecules, in contrast to lipid-soluble signal molecules, tend to move more readily through interstitial space, one of the issues associated with any water-soluble signal molecule is how can its presence influence the internal workings of any cells. (T/F)

True, Water-soluble signals cannot cross the cell membrane on their own, so they need cell-surface receptors to pass messages inside.

A very important water-soluble signal molecule released by some cells into interstitial space (where it can travel to other cells) is called cyclic AMP. Adenylate cyclase is the name given to the enzyme that initially converts ATP into cyclic AMP. And phosphodiesterase is the name given the enzyme that converts cyclic AMP into AMP, hence shutting down its signal molecule activity. (T/F)

False, cyclic AMP (cAMP) is an intracellular second messenger, not a signal molecule released into the interstitial space to travel between cells.

The common result associated with the opening of ligand-gated calcium ion channels on the outer membrane of a cell is that all proteins within the cell undergo a shape change. (T/F)

False, Incoming signals change only specific target proteins, not every single protein in the cell.

Four ways that membrane bound ion channels are known to be opened are: binding with a signal molecule, binding with a G-protein, binding with cyclic AMP, or being phosphorylated. (T/F)

true, on channels can be opened by signaling molecules, G-proteins, cyclic AMP, or phosphorylation.

Signaling pathways that involve the activation of an enzyme known as phospholipase C tend to alter a cell in two distinct ways: the activation of a protein kinase, and an increase in the cytoplasm concentration of calcium ions. Both of which can alter the activity of other proteins within the cell. (T/F)

True, Phospholipase C activates a protein kinase and raises internal calcium levels.

Increasing blood glucose levels triggers certain pancreatic cells (known as beta cells) to release a hormone known as insulin. Many cells in the body are unaffected by rising insulin levels, but for those cell types that are, the general response is to increase the rate that they bring circulating glucose molecules into their cells. Given this effect, it would make sense to consider the insulin receptors on these cells as being “negative sensors”. (T/F)

false, Insulin receptors help maintain balance, but they are not classified as "negative sensors." They are in a negative feedback loop though

A common design feature within the regulatory pathways that control the release of thyroid hormone, cortisol, and sex steroids is: Signal molecules released into the blood stream from a brain region known as the hypothalamus, in turn, trigger the release of signal molecules into the blood stream from a gland known as the anterior pituitary. (T/F)

True, Hormones from the hypothalamus tell the anterior pituitary to release its own hormones.

A common feature of thyroid hormone, cortisol, and sex steroids is that their release into circulation is triggered by a tropic hormone. Furthermore, the release of each of these three lipid-soluble hormones acts to further increase the release of the tropic hormone that triggers their release. (T/F)

False, These hormone pathways use negative feedback, meaning the final hormone shuts off (rather than increases) its upstream trigger.

endocytosis

something entering a cell, passing through a membrane, the taking in of living matter by a cell

exocytosis

something leaving a cell, passing through a membrane
a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

epithelium

type of tissue that lines the surfaces and cavities of your body's organs

ectoderm

outside sheet of cells in epithelium

endoderm

inside sheet of cells in epithelium the epithelium that lines the gut cavity or gut tube of a two- or three-layered animal.

mesoderm

a third layer sandwiched between an ectoderm and endoderm, not diffusion friendly

interstitial space

space inside an epithelium (two membranes) but outside the cells

gut cavity

space with epithelium surrounding, with just entrance that acts as mouth and anus, has interstitial space between epithelium

gut tube

space with two epithelium surrounding each side, with one entrances that acts as mouth and one exit that acts as anus, has interstitial space between epitheliums

homeostasis

the act of maintaining similar conditions despite constant disruptive fluctuations

sensor

any device that adjusts a processor's rate as a response to detecting some change in conditions, detects changes in the environment

scarce resource

tends to be lost from the body, and once lost is difficult to replace-- work is required to get more
-ex: oxygen

excessive resource

tends to be added to the body, and once added is difficult to get rid of-- work is required to remove it
-ex: carbon dioxide

counter-acting response

when a sensor that detects some trend of change initiates rate adjustments that act to reverse
the trend
-trend reversing, negative feedback
ex: keep baby in labor

co-acting response

tend maintaining, positive feedback
ex: get baby out in labor

paracrine system

Chemical signals secreted by cells can act over varying distances. In this signaling, molecules act on nearby cells.
an endocrine function in which effects of a hormone are localized to adjacent or nearby cells.
-moves to target cells by diffusion

endocrine system

The collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things
-uses convection to travel to distant target cells

hormone

any chemical signal that uses the circulatory system to travel between the monitor that released it and whatever effectors respond to it

neurotransmitter

any chemical signal released from the end of a nerve cell that has a direct effect on whether the postsynaptic cell will fire an action potential.

solution

a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent)

solvent

what solutes dissolve in

solute

any chemical that is dissolved (suspended within) a solvent

osmole

the total number of particles (in terms of moles)
suspended within the solution. (Note: the size of the particle is irrelevant, which means an atomic ion or a very large dissolved molecule both count as one particle.)

acid

A substance that increases the hydrogen ion concentration of a solution.
Any compound that increases the number of hydronium ions when dissolved in water

base

A substance that decreases the hydrogen ion concentration in a solution.
Any compound that increases the number of hydroxide ions when dissolved in water

buffer

Something that minimizes changes in pH by associating with (binding with) hydrogen ions when their concentration increases, and dissociating with (releasing) hydrogen ions when their concentration decreases.

enzyme

any protein that acts as a catalyst for a specific chemical reaction.

permease

any protein that aids in the movement of a specific type of molecule across a cell membrane.

desmosome

a structure by which two adjacent cells are attached, formed from protein plaques in the cell membranes linked by filaments.

tight junction

a connection between two cells that forms a sufficiently tight seal that even most small molecules are
prevented from moving from one side of an epithelium to the other by leaking through the spaces between cells.

gap junction

small tube like structures made of protein (a channel protein) that create a direct connection between the
cytoplasm of adjacent cells.

connective tissue

Regions of interstitial space with few cells and lots of extracellular matrix. (Note: the extracellular matrix typically contains a network of molecules involved in providing structural support to the organism.)

interstitial fluid

the fluid in spaces between the tissue cells

ATP

Adenosine triphosphate is a nucleoside triphosphate used in cells as a coenzyme often called the "molecular unit of currency" of intracellular energy transfer. transports chemical energy within cells for metabolism. ATP is the way your body uses biochemicals to store and use energy

higher phosphorylation potential

a molecule (base-group) that in comparison to another molecule does not hold onto certain phosphates as tightly, so (during a chemical reaction) more readily donates a phosphate (to this other molecule) than accepts a phosphate (from this other molecule).

orthophosphate

Orthophosphate is a simple, dissolved form of phosphorus (PO₄³⁻) that plants can use immediately and that public water systems add to prevent lead and copper from dissolving into tap water

protein kinase

the generic name given to any of the enzymes that catalyzes the transfer of a phosphate from ATP to a
protein.

protein phosphate

the generic name given to any of the enzymes that catalyzes the transfer of a phosphate from a
protein to water

creatine

a molecule with similar phosphorylation potential as ADP that is used to store high-energy (or weakly held)
phosphates whenever ATP is currently in excess (by accepting a phosphate to become phosphocreatine) and releasing
that stored energy whenever ATP is currently scarce ( by donating the phosphate back to an ADP to form ATP).

fermentation (glycogen-lactic acid system)

Glycogen is a chain of glucose molecules; the glycogen is split into glucose by cells. Then cells use anaerobic metabolism (meaning "without oxygen") to make ATP. A byproduct from the glucose is called lactic acid.

aerobic respiration

the form of respiration which uses oxygen. It can be summarized by this equation: glucose + oxygen → carbon dioxide + water (+ energy)

Anaerobic respiration

is a form of respiration using electron acceptors other than oxygen. Although oxygen is not used as the final electron acceptor, the process still uses a respiratory electron transport chain; it is respiration without oxygen.

deamination

when the amine group is removed from a molecule (commonly an amino acid) and converted to
ammonia.

metabolic water

the name given to water molecules formed whenever molecular oxygen acts as a final acceptor in a respiratory electron transport chain. In other words, it is the water formed as oxygen accepts electrons (accompanied by protons, or in total hydrogen atoms) out of the final step of the electron transport chain, which is part of aerobic respiration.

keratinocytes

only cells that can divide and make more cells in the epithelium
-split into 2 and one moves up to replace dead cells

tonicity

the relative osmolarity of the solution surrounding the cell in comparison with the solution inside the cell
-determine the direction and extent of diffusion.

isotonic

-solution having the same osmotic pressure as some other solution
-The concentration of solutes is equal inside and outside the cell so water moves across the membrane in both directions maintaining cell size

hypotonic

the solution has a lower solute concentration than the cell so water moves into the cell causing plant cells to swell and animal cells to swell and burst
-water always try to go and dilute where there are too many particles

hypertonic

the solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to plasmolyze
-water always try to go and dilute where there are too many particles

concentration gradient

a change in concentration across distance (biology means a change across a membrane)

simple diffusion

net directional movement of some type of molecule across a membrane where the movement is powered by the presence of a concentration gradient (high to low), and the molecules cross simply because the membrane is permeable to this type of molecule

facillitated diffusion

net directional movement of some type of molecule across a membrane where movement is powered by the presence of a concentration gradient (movement from high to low) and the molecules cross the membrane with the aid of a chanel protein or permease

active transport

net directional movement of some type of molecules across a membrane where the movement goes against the concentration gradient so the movement is powered by a usable energy source supplied bu the cell (Specifically ATP), and the molecules cross the membrane with the aid of a permease

secondary active transport

a two staged transport mechanism where first a concentration gradient of some chemical (typically sodium ions) is established by active transport, an d then the transmembrane flow of this same chemical with its concentration gradient is used as the energy source to power transmembrane movement of some other molecule against its concentration gradient

co-transport (antiport)

a type of secondary active transport where a membrane protein moves one molecule down its concentration gradient to power the movement of another molecule against its gradient. It doesn’t use ATP but instead uses the electrochemical gradient created by primary active transport pumps

counter-transport (symport)

a type of secondary active transport mechanism where a membrane protein moves two or more different molecules or ions across a cell membrane in the same direction at the same time

receptor-mediated endocytosis

the endocytosis of a certain molecule type occurs due to the molecule binding to a membrane bound protein, which triggers the chain of events leading to endocytosis

exocytosis

an active transport process where a cell moves large molecules, proteins, or waste out through its cell membrane. The cells must be in a membrane bound sac called the vesicle

secretory vesicle

an active transport process where a cell moves large molecules, proteins, or waste out through its cell membrane (e.g. neurotransmitters, hormones, and enzymes)

osmotic pressure

the minimum pressure needed to stop a solvent from flowing into a solution through a semipermeable membrane

osmosis

the diffusion of solvent molecules (water molecules) towards regions of higher osmotic concentration (hence regions of lower water concentration)

membrane potential

the electrical voltage difference between the inside and the outside of a biological cell

depolarization

the reduction of a cells membrane, the reuction of the overall seperation of charge

hyperpolarization

a change in a cell's membrane potential that makes the inside of the cell more negative than its normal resting state

ligand

the genaric name for a molecule that has the right shape to bind with a protein

ligand-gated ion channel

(ion channel linked receptor, chemically activated ion channel) a channel that opens via the binding of a specific type of molecule (a. ligand) to some part of the channel

enzyme-linked receptor

a membrane-bound receptor that upon binding to its ligand (on the outside of the cell) activates an enzyme on the cytosolic or inside of the cell that is part of the same membrane-spanning complex (as the receptor)

g-protein-linked receptor

a membrane bound receptor that upon binding to its ligand (on the outside of the cell) activates a g-protein on the cytosolic or inside of the cell

second messenger

an intracellular chemical whose formation is triggered by the binding of a ligand to a membrane bound receptor, and once formed triggers change (often a whole series of changes) within the workings of the cell

adenylate cyclase

an enzyme that catalyzes the conversion of ATP to cyclic AMP/cAMP

cyclic AMP

a crucial second messenger molecule that helps cells respond to external signals like hormones and neurotransmitters, derrived from ATP (binds to a g-coupled receptor on the cells outer membrane)

Protein Kinase A

a key cellular enzyme whose activity depends on the signaling molecule cyclic AMP (cAMP). It modifies other proteins by adding phosphate groups to them, which controls vital processes like energy metabolism, gene expression, and cell growth

Guanylate cyclase

an enzyme that turns guanosine triphosphate (GTP) into cyclic guanosine monophosphate (cGMP)

cyclic GMP

a vital intracellular second messenger derived from guanosine triphosphate (GTP) that transmits and amplifies signals inside cells

Phospholipase C

an enzyme that catalyzes the splitting of a specific type of phospholipid into IP3 and DAG (both which act as a second messenger molecule)

inositol triphosphate (IP3)

a water-soluble second messenger molecule that triggers the release of calcium ions into the cell's cytoplasm